The present invention relates to a waste water treatment method and waste water treatment equipment capable of treating the organic matter discharged from a semiconductor plant, a liquid crystal plant or the like, and in particular, fluorine waste water containing a surface active agent, nitrogen, phosphor and hydrogen peroxide of poor biodegradability. The present invention relates, in particular, to a waste water treatment method and waste water treatment equipment that generates little sludge (waste) and is able to treat the waste water by reusing chemicals.
In a semiconductor plant, liquid crystal plant or the like, surface active agents are mixed in various chemicals for use in the production apparatuses in line with the rapid progress in microstructure. It is general to use nitric acid, ammonia water, phosphoric acid, hydrogen peroxide and hydrofluoric acid in the manufacturing equipment of the semiconductor plant or the like. Among others, the amount of use of hydrofluoric acid tends to be generally great as compared with the other chemicals. For the above reasons, the fluorine waste water containing a surface active agent, nitrogen, phosphor, hydrogen peroxide and so on is discharged from the production rooms of the plant. It is to be noted that the fluorine waste water is an acid waste water that has fluorine as a main ingredient and contains a small amount of surface active agent, nitrogen, phosphor and hydrogen peroxide.
As described above, under the conditions of the rapid progress in microstructure of semiconductor devices, a surface active agent is used since aqueous cleaning by means of ultrapure water cannot sufficiently clean the minute portions due to the surface tension of water. For this reason, the surface active agent is mixed in the waste water.
As described above, in the semiconductor plant or the like, a method for cleaning the minute portions through the reduction of the surface tension by mixing a surface active agent into ultrapure water and a method for executing cleaning through the reduction of the surface tension by mixing a surface active agent into a variety of chemicals for cleaning use are gaining popularity. For example, a chemical such as buffered hydrofluoric acid containing a surface active agent is used. A variety of surface active agents to be mixed in the chemical are the important know-how of each chemical manufacturer, and newly-developed surface active agents are opportunely used. The newly-developed surface active agents include those of poor biodegradability in terms of the molecular formula, structural formula, effervescence, sterilizing performance and so on of the substance. Therefore, the conventional activated sludge method, catalytic oxidation method or the like as a representative of the biotic treatment become unable to cope with the decomposition treatment since the methods have a low microorganic concentration of about 2000 ppm to 5000 ppm.
Then, the latest report says that some surface active agents might become hormone disrupters, and prompt countermeasures are required.
The waste water also contains nitrogen and phosphor attributed to nitric acid, ammonia water and phosphoric acid, and it is required to treat the nitrogen and phosphor from the point of view of eutrophication and red tide. However, the general denitrification equipment and dephosphorization equipment disadvantageously require high initial cost and running cost.
The waste water also contains hydrogen peroxide, and in order to treat the hydrogen peroxide that serves as an oxidizing agent in the waste water, a treatment method using sodium bisulfite added as a reductant and a treatment method using activated carbon as a catalyst. However, those methods also require high initial cost and running cost.
In this age where environmental conservation is regarded as important, it is an important urgent problem that the enterprises should tackle to reuse the used chemicals and reduce waste generated from the plants for the achievement of cost reduction.
Conventionally, as a waste water treatment method for reusing the sludge including unreacted chemicals, there have been proposed the following methods (1), (2) and (3).
(1) First prior art: Japanese Patent Laid-Open Publication No. HEI 6-343974.
(2) Second prior art: Japanese Patent Laid-Open Publication No. HEI 8-197070.
(3) Third prior art: Japanese Patent Laid-Open Publication No. HEI 10-5769.
Each of the above three waste water treatment methods sends the sludge precipitated in the sedimentation tank back to the reaction tank or the coagulation tank, in which a stirrer is placed.
According to the first prior art, stirring is executed by stirring use air concurrently with stirring by the stirrer, however, the retention time is short. By comparing the stirring that continues for a short retention time (20 minutes, for example) by a stirrer to the stirring with a long reaction time (2 hours, for example) by air, it was discovered that the latter was more efficient in releasing calcium ions and aluminum ions from the hydroxide in the sludge particularly when utilizing again the sludge by sending back.
The fundament of the treatment of fluorine waste water is to form slightly-soluble calcium fluoride for the treatment. For the purpose of reducing the sludge that is the waste generated from the waste water treatment equipment, a method for using calcium carbonate mineral is adopted instead of the conventional slaked lime method for using slaked lime.
What is important in this case is that the fundament of the treatment of fluorine is to form slightly-soluble calcium fluoride and remove the same. If the slightly-soluble calcium fluoride is formed, then the calcium fluoride is not redissolved under either acid condition or alkali condition. That is, if the calcium fluoride that becomes the cores of flocs by reusing again and again the calcium agent (slaked lime or calcium carbonate mineral), then the waste generated from the waste water treatment equipment can be reduced. Furthermore, the chemicals can be reused to allow the waste water treatment to be efficiently achieved.
The sludge as the conventional waste also includes the aforementioned calcium fluoride, however, a large amount of unreacted slaked lime and unreacted coagulant has existed.
As a prior art that uses calcium carbonate, there is a fourth prior art reference (Japanese Patent Laid-Open Publication No. HEI 7-136667). According to this method, fluorine-containing water is made to serially flow through a plurality of towers filled with calcium carbonate, and after the outflow water of each tower filled with calcium carbonate is aerated, part of the water is made to flow again through the same tower filled with calcium carbonate. According to this fourth prior art example, by aerating the outflow water of each tower filled with calcium carbonate, CO2 gas from CaCO3 contained in this outflow water is discharged. By subsequently making the water flow again through the same tower filled with calcium carbonate, the amount of CaCO3 that flows into the tower filled with calcium carbonate is reduced as far as possible. Through the above treatment, the amount of addition of the alkali agent of ammonia, ammonium fluoride or the like for the prevention of the collapse of the calcium carbonate filler material due to CaCO3 can be reduced.
As a fifth prior art example, there is a xe2x80x9cmethod for treating fluorine-containing organic waste waterxe2x80x9d disclosed in the prior art reference of Japanese Patent Laid-Open Publication No. HEI 5-4090. According to this treatment method, although the calcium carbonate mineral is not used, the water-soluble calcium compound of slaked lime, calcium chloride or the like is added to the fluorine-containing organic waste water so as to coagulate and precipitate the calcium fluoride. After adjusting pH of the supernatant liquid to 6.5 to 7.0, the water is brought in contact with fixed microorganic pellets to undergo an aeration treatment for the removal of BOD components. Subsequently, a coagulant is added to precipitate the microorganism leaked from the pellets together with the remaining fluorine compound. According to this fifth prior art example, the fluorine-containing organic waste water is subjected to a coagulo-sedimentation treatment, and thereafter the liquid pH is adjusted to 6.5 to 7.0 and then brought in contact with the fixed microorganic pellets. Therefore, the adhesion of calcium to the micropores of the fixed microorganic pellets is prevented, as a consequence of which a high rate of removal of fluorine and BOD can be achieved.
As a sixth prior art example, there is xe2x80x9cwaste water treatment equipment and waste water treatment methodxe2x80x9d disclosed in the prior art reference of Japanese Patent Laid-Open Publication No. HEI 9-174081. This sixth prior art example can treat fluorine waste water containing organic matter. As shown in FIG. 15, this waste water treatment equipment is provided with a first water tank 151 that has an upper portion 151A and a lower portion 151B. The first water tank upper portion 151A has an air diffusion pipe 152A and is filled with granular calcium carbonate mineral 157. The granular calcium carbonate mineral 157 of the first water tank upper portion 151A is made to strongly flow by aeration, by which the fluorine in the waste water chemically reacts with the calcium carbonate mineral 157 and becomes calcium fluoride, treating the fluorine in the waste water. On the other hand, a microorganism propagates on the surface of the granular calcium carbonate mineral 157 that has subsided from the first water tank upper portion 151A to the first water tank lower portion 151B, thereby biologically treating the organic matter in the waste water.
The granular calcium carbonate mineral 157 that has moved to the lowermost portion of the first water tank lower portion 151B moves toward the first water tank upper portion 151A while being mixed with the waste water by an air lift pump 155 placed in the lower portion 151B and chemically treats the fluorine in the waste water. A biotic sludge 156 and an inorganic sludge 200 comprised mainly of calcium fluoride, which are generated in the first water tank 151, are subjected to a coagulation treatment with polychlorinated aluminum added as an inorganic coagulant. Subsequently, each sludge moves to a sedimentation tank 163 so as to be subjected to solid-liquid separation into sludge as a precipitate and a treated water as a supernatant liquid.
As a seventh prior art example, there is xe2x80x9cwaste water treatment equipment and waste water treatment methodxe2x80x9d disclosed in the prior art reference of Japanese Patent Laid-Open Publication No. HEI 8-57498. This seventh prior art example can concurrently treat the waste water and exhaust gas, which contain fluorine and a surface active agent. According to this seventh prior art example shown in FIG. 16, a calcium carbonate mineral 146 is placed in a lower portion of a first reaction regulation tank 131, while the calcium carbonate mineral 146 and a plastic filler 148 are placed in an upper portion of the first reaction regulation tank 131. The calcium carbonate mineral 146 and charcoal 147 are placed in a lower portion of a second reaction regulation tank 132, while the charcoal 147 and a plastic filler 148 are placed in an upper portion of the second reaction regulation tank 132. A waste water containing fluorine and a surface active agent is firstly aerated and stirred in the lower portion of the first reaction regulation tank 131, then sprinkled in the upper portion of the first reaction regulation tank 131 and subsequently aerated and stirred in the lower portion of the second reaction regulation tank 132. The waste water is further sprinkled in the upper portion of the second reaction regulation tank 132, subsequently subjected to the coagulation treatment with added coagulant and then subjected to solid-liquid separation into a sludge as a precipitate and a supernatant liquid in a sedimentation tank 134. It is to be noted that the mixed sludge that includes inorganic sludge, organic sludge and biotic sludge as the sludges precipitated in the sedimentation tank 134 is sent back to the upper portion of the first reaction regulation tank 131 and sprinkled so as to be used for the treatment of the waste water and the exhaust gas.
As described above, the acid waste water discharged from the general semiconductor plant for fabricating integrated circuits includes fluorine as a main ingredient, organic matter such as a surface active agent as an ingredient having poor biodegradability, IPA (isopropyl alcohol), acetone, nitrogen attributed to nitric acid and ammonia water, phosphor attributed to phosphoric acid and hydrogen peroxide as an oxidizing agent.
Among others, with regard to, in particular, the surface active agent serving as the organic matter mixed in the chemicals, new products are opportunely developed with the progress in microstructure and mixed in the chemicals for use in a variety of production apparatuses. Accordingly, there are appearing products (i.e., surface active agents having poor biodegradability) that cannot easily be treated by microorganism at low microorganic concentration (2000 to 5000 ppm) by the conventional activated sludge method or the catalytic oxidation method.
In particular, according to the latest information, the aforementioned surface active agents, which might be a hormone disrupter, must be reliably decomposed by treatment.
Nitrogen and phosphor, which are the cause of eutrophication and red tide, are also required to be reliably treated.
The hydrogen peroxide in the waste water, which increases COD (Chemical Oxygen Demand) that is a discharge control item, must be controlled within a control value by treatment.
On the other hand, there is a tend toward substantially reducing the waste generated from each plant, and some plants have achieved the so-called zero emission for the total elimination of waste generated from the plants. Therefore, when treating the acid waste water in a semiconductor plant, there is needed a waste water treatment system for reducing the waste as far as possible.
A waste water treatment method for treating fluorine in the acid waste water has a first step for forming slightly-soluble calcium fluoride by adding the calcium agent of slaked lime, calcium carbonate mineral or the like, thereby treating the fluorine in the waste water to a concentration of about 20 to 40 ppm (this is the lower limit of treatment in the present circumstances). In a second step, the waste water obtained through the first step that can treat fluorine to a concentration of about 20 to 40 ppm at the utmost is thereafter treated down to the intended fluorine concentration (5 to 15 ppm) by adding an inorganic coagulant of polychlorinated aluminum or the like and subsequently adding a macromolecular coagulant.
However, in the second step, the fluorine concentration cannot be reduced to the intended concentration unless a large amount of inorganic coagulant such as polychlorinated aluminum or a large amount of macromolecular coagulant is added with respect to the amount of fluorine in the waste water (the achievement in the field of water treatment). Therefore, the unreacted polychlorinated aluminum, the macromolecular coagulant and so on precipitate together with the slightly-soluble calcium fluoride, and they become included in the sludge.
In view of the above, the unreacted polychlorinated aluminum and the unreacted macromolecular coagulant included in the sludge are sent back to the reaction tank or the coagulation tank so as to be reused. For example, the second prior art example (Japanese Patent Laid-Open Publication No. HEI 8-197070) sends the sludge back to the reaction tank.
However, those tanks, where stirring is executed by the stirrer, have small effect for loosening the sludge and have a short retention time. Therefore, the unreacted chemicals from the sludge cannot completely be regenerated as calcium ions and aluminum ions, and this has led to poor regeneration efficiency.
The third prior art example (Japanese Patent Laid-Open Publication No. HEI 10-5769) sends the sludge back to the coagulation tank that has a short retention time similarly to the reaction tank, instead of the reaction tank. This method has the problem that the sludge does not easily loosen, resulting in poor regeneration efficiency.
In view of the above, as an eighth prior art example, there is the one shown in FIG. 18. This eighth prior art example is a prior art method for treating a fluorine waste water containing a surface active agent, phosphor and hydrogen peroxide using general calcium carbonate mineral. The surface active agent serving as the organic matter in the waste water is somewhat decomposed by the aerobic microorganism in a second water tank 193. However, for the reason that the microorganic concentration is low and the biodegradability of the surface active agent is poor in the second water tank 193, it has been impossible to secure a sufficient ratio of decomposition and removal of the surface active agent. Specifically, the removal ratio of the surface active agent in the second water tank 193 is intended to be 50% or higher, whereas the waste water treatment equipment shown in FIG. 18 has not been able to secure a surface active agent removal ratio of 50%.
The hydrogen peroxide in the waste water is more or less decomposed by the anaerobic microorganism propagating in the third water tank 195 through the sixth water tank 198, whereas the removal ratio regarding the decomposition of hydrogen peroxide has practically been not greater than 50%.
Although an removal ratio of not lower than 90% of phosphor in the waste water has been able to be achieved since slaked lime is added to the third water tank 195. However, in order to secure the removal ratio, there has been the problem that the slaked lime is required to be excessively added in terms of concentration more than is needed for phosphor in the waste water. That is, the slaked lime added to the third water tank 195 tends to easily flow without sinking, and the unreacted slaked lime flows out of the third water tank 195 toward the fourth water tank 196 since the reaction time has a duration of not longer than one hour instead of a duration of not shorter than several hours.
The same thing can be said for not only the slaked lime but also the polychlorinated aluminum added to the fourth water tank 196 and the macromolecular coagulant added to the fifth water tank 197. As a result, the unreacted coagulant sludge (i.e., hydroxide sludge of calcium hydroxide, aluminum hydroxide and so on) attributed to the slaked lime, polychlorinated aluminum and macromolecular coagulant exists in the sludge precipitated in the sixth water tank 198, causing an increase in the amount of generated sludge.
As described above, according to the waste water treatment method of the eighth prior art example, the amount of generated sludge is reduced as compared with the waste water treatment method for executing treatment with the slaked lime and the coagulant without using the calcium carbonate mineral 191. However, the unreacted slaked lime and the unreacted coagulant are still contained in the sludge. Therefore, this waste water treatment method is not the most appropriate waste water treatment method in the current age of waste reduction, and the reuse of the unreacted slaked lime and the unreacted coagulant has been a big problem.
Accordingly, the present invention has the following objects (1) through (5).
(1) An object is to highly efficiently treat the surface active agent in the waste water.
(2) An object is to efficiently treat the nitrogen in the waste water.
(3) An object is to reuse the unreacted polychlorinated aluminum and macromolecular coagulant.
(4) An object is to efficiently treat the hydrogen peroxide and phosphor in the waste water.
(5) An object is to reduce the waste generated from the waste water treatment equipment.
In order to achieve the aforementioned object, there is provided a waste water treatment method for treating a fluorine waste water containing organic matter, nitrogen, phosphor and hydrogen peroxide by introducing the waste water into an anaerobic tank and an aerobic tank, comprising: a calcium carbonate mineral placed in the anaerobic tank; a biologically treated water of another system introduced into the aerobic tank; and a calcium carbonate mineral placed in the aerobic tank.
According to this constitution of the present invention, the organic matter can be treated in the anaerobic tank. If nitrate nitrogen exists, then the denitrification can be achieved by using the organic matter as a hydrogen donor. The organic matter in the waste water can be treated in the aerobic tank, and if ammoniacal nitrogen and nitrite nitrogen exist in the waste water, then the nitric substances can be aerobically oxidized to the nitrate nitrogen. By the microorganism included in the biologically treated water of another system introduced into the aerobic tank, the organic matter can be efficiently biologically treated.
In an embodiment of the present invention, the organic matter is a surface active agent having poor biodegradability.
According to this embodiment, the biologically treated water introduced into the aerobic tank includes a microorganism. Therefore, the surface active agent having poor biodegradability can be more easily decomposed than in the case where the surface active agent is treated by only the microorganism that is naturally generated and propagated.
In an embodiment of the present invention, the biologically treated water is a treated water obtained by biologically treating a waste water containing a high-concentration surface active agent.
According to this embodiment, the biologically treated water of another system is the treated water obtained by biologically treating the waste water containing a high-concentration surface active agent. Therefore, the microorganism included in the biologically treated water is the microorganism more appropriate for the treatment of the surface active agent. The microorganism is plentifully contained in the biologically treated water, and therefore, the surface active agent in the waste water can be efficiently treated.
In an embodiment of the present invention, the biologically treated water is a treated water obtained by biologically treating a waste water containing a developing solution.
According to this embodiment, the biologically treated water is the treated water obtained by biologically treating the waste water containing a developing solution. This waste water containing a developing solution generally includes a high-concentration surface active agent, and the surface active agent in the waste water can be efficiently treated. The waste water containing a developing solution exists in almost all the IC plants, and the waste water can be treated by effectively utilizing the biologically treated water from the biological treatment equipment of another system for biologically treating the waste water containing a developing solution.
Also, there is provided waste water treatment equipment wherein a fluorine waste water containing organic matter, nitrogen, phosphor and hydrogen peroxide is chemically and biologically treated and thereafter treated by being introduced into a biotic activated carbon tank and a biotic activated carbon tower having a biotic activated charcoal and a biotic activated carbon.
According to this constitution of the present invention, the waste water is chemically and biologically treated and thereafter further biologically and physically treated by the biotic activated carbon tank and the biotic activated carbon tower having a biotic activated carbon and a biotic activated charcoal. Therefore, in particular, the organic matter can be highly and reliably treated.
The biotic activated carbon tank means a treatment tank in which both the Bincho charcoal that serves as a charcoal and the activated carbon are placed and the microorganisms are propagated on the surfaces of these fillers, providing the practical effect of regenerating the organic matter component absorbed by the Bincho charcoal and the activated carbon. The biotic activated carbon tower means an activated carbon tower in which the microorganism is propagated on the activated carbon and the organic matter adsorbed by the activated carbon is treated by the propagated microorganism, providing the practical effect of automatically regenerating the activated carbon. Therefore, the biotic activated carbon tank and the biotic activated carbon tower are not required to be regenerated even after a lapse of a specified period. In contrast to this, in the activated carbon tower of the general waste water treatment equipment, the activated carbon is taken out with the frequency of once three to six months and regenerated in the other place.
In an embodiment of the present invention, the anaerobic tank has an upper portion constructed of an anaerobic sludge zone and a lower portion constructed of a calcium carbonate mineral zone, and the aerobic tank has an upper portion constructed of an aerobic sludge zone and a lower portion constructed of a calcium carbonate mineral zone.
According to this embodiment, the nitrate nitrogen can be denitrified in the anaerobic sludge zone in the upper portion of the anaerobic tank, and the organic matter and the hydrogen peroxide can be further treated. The fluorine can be treated in the calcium carbonate mineral zone in the lower portion of the anaerobic tank. The organic matter can be treated in the aerobic sludge zone in the upper portion of the aerobic tank, and the fluorine can be treated in the calcium carbonate mineral zone in the lower portion of the aerobic tank.
In an embodiment of the present invention, the anaerobic sludge zone in the upper portion of the anaerobic tank has a sludge that includes an unreacted slaked lime, an unreacted polychlorinated aluminum, an unreacted macromolecular coagulant, a generated calcium fluoride and a microorganism, and the aerobic sludge zone in the upper portion of the aerobic tank has a sludge that includes an unreacted slaked lime, an unreacted polychlorinated aluminum, an unreacted macromolecular coagulant, a generated calcium fluoride and a microorganism.
According to this embodiment, the sludge in the anaerobic sludge zone in the upper portion of the anaerobic tank includes the unreacted slaked lime, unreacted polychlorinated aluminum, unreacted macromolecular coagulant, generated calcium fluoride and microorganism. Therefore, phosphor can be treated as calcium phosphate by the unreacted slaked lime. The calcium fluoride formed through the reaction of fluorine with the calcium carbonate mineral in the lower portion of the anaerobic tank can be formed into larger and more stable flocs by the unreacted polychlorinated aluminum and the unreacted macromolecular coagulant.
The sludge in the aerobic sludge zone in the upper portion of the aerobic tank is a sludge that includes the generated calcium fluoride and the microorganism. Therefore, the organic matter can be aerobically treated.
The sludge in the aerobic sludge zone in the upper portion of the aerobic tank includes the unreacted slaked lime, unreacted polychlorinated aluminum, unreacted macromolecular coagulant, generated calcium fluoride and microorganism. Therefore, phosphor can be treated as calcium phosphate by the unreacted slaked lime similarly to the anaerobic tank. The calcium fluoride formed through the reaction of fluorine with the calcium carbonate mineral in the lower portion of the aerobic tank can be formed into larger and more stable flocs by the unreacted polychlorinated aluminum and the unreacted macromolecular coagulant. The sludge in the aerobic sludge zone in the upper portion of the aerobic tank is a sludge that includes the generated calcium fluoride and the microorganism. Therefore, the organic matter can be aerobically treated.
As described above, according to this embodiment, the waste water can be treated without using any new chemical in both the anaerobic tank and the aerobic tank.
In an embodiment of the present invention, the sludge is a return sludge from a sedimentation tank of waste water treatment equipment.
According to this embodiment, the sludge is the return sludge from the sedimentation tank of the waste water treatment equipment. Therefore, the sludge including the unreacted slaked lime, unreacted polychlorinated aluminum, unreacted macromolecular coagulant, generated calcium fluoride and microorganism can be easily secured as the return sludge from the waste water treatment equipment through no special process and utilized for waste water treatment.
The return sludge has an increased sludge concentration through the sedimentation process in the sedimentation tank, and in addition, the sedimentation tank has no aeration process. Therefore, the microorganisms mainly comprised of the anaerobic microorganism are propagating in this return sludge. Therefore, if the sludge is sent back to the anaerobic tank (second water tank), then the waste water can be efficiently treated by this return sludge having a high sludge concentration.
Since there is existing no aeration process in the anaerobic tank (second water tank), the degree of anaerobic property is increased further than in the sedimentation tank. Consequently, the anaerobic microorganism propagates and increases to allow the waste water to be anaerobically treated. The return sludge from the sedimentation tank is also sent back and introduced into the aerobic tank (third water tank). Since the aeration process is existing in this aerobic tank, the aerobic microorganism gradually propagates and increases to allow the waste water to be aerobically treated.
In an embodiment of the present invention, the microorganism in the anaerobic sludge zone of the anaerobic tank is an anaerobic microorganism, and the microorganism in the aerobic sludge zone of the aerobic tank is an aerobic microorganism.
According to this embodiment, the microorganism existing in the anaerobic sludge zone of the anaerobic tank is the anaerobic microorganism. Therefore, the nitrate nitrogen can be denitrified using the organic matter in the waste water as a hydrogen donor, and the surface active agent serving as the organic matter can also be concurrently treated. Furthermore, the hydrogen peroxide can be treated by the reducibility owned by the anaerobic microorganism. The microorganism existing in the aerobic sludge zone of the aerobic tank is the aerobic microorganism. Therefore, the ammoniacal nitrogen and the nitrite nitrogen in the waste water can be oxidized to the nitrate nitrogen, and the surface active agent serving as the organic matter can also be concurrently treated by the aerobic microorganism.
Also, there is provided waste water treatment equipment comprising: a first water tank into which the fluorine waste water containing organic matter, nitrogen, phosphor and hydrogen peroxide is firstly introduced; a second water tank in which a calcium carbonate mineral is placed and into which the return sludge is introduced; a third water tank which has a stirring means and a calcium carbonate mineral placed therein and into which the return sludge and the biologically treated water are introduced and mixed; a fourth water tank to which slaked lime is added; a fifth water tank to which polychlorinated aluminum is added; a sixth water tank to which a macromolecular coagulant is added; a seventh water tank that serves as a sedimentation tank; and an eighth water tank that serves as a condensation tank, the waste water to be treated being sequentially introduced into the first, second, third, fourth, fifth, sixth, seventh and eighth water tanks.
According to this constitution, the fluorine in the waste water can be treated as calcium fluoride by the calcium carbonate mineral placed in the second water tank, and the waste water can also be treated by the components in the return sludge.
The fluorine in the waste water can be efficiently treated as calcium fluoride by the calcium carbonate mineral placed in the third water tank by stirring the waste water by the stirring means. Furthermore, the waste water that is being stirred can be efficiently treated by the components in the return sludge to the third water tank. Furthermore, the biologically treated water is introduced and mixed in the third water tank, and therefore, the microorganism in the biologically treated water facilitates the treatment of, in particular, the organic matter.
In the fourth water tank to which slaked lime is added, the phosphor in the waste water can be treated into calcium phosphate.
In the fifth water tank to which polychlorinated aluminum is added, the formed minute calcium fluoride and the calcium phosphate come to have a floc form.
In the sixth water tank to which a macromolecular coagulant is added, the flocs formed in the fifth water tank can be formed into larger stable flocs.
In the seventh water tank (sedimentation tank), a treated water can be obtained as a supernatant liquid by precipitating the sludge that serves as a solid matter in the waste water.
In the eighth water tank (condensation tank), the sludge that serves as the solid matter precipitated in the seventh water tank (sedimentation tank) can be further condensed to allow the sludge concentration to be increased. In addition, the sedimentation tank and the condensation tank are supplied with no oxygen, and therefore, the anaerobic microorganism can be cultured and propagated in the sludge.
Also, there is provided waste water treatment equipment comprising: a first water tank into which the fluorine waste water containing organic matter, nitrogen, phosphor and hydrogen peroxide is firstly introduced; a second water tank in which a calcium carbonate mineral is placed and into which the return sludge is introduced; a third water tank which has a stirring means and a calcium carbonate mineral placed therein and into which the return sludge and the biologically treated water are introduced and mixed; a fourth water tank to which slaked lime is added; a fifth water tank to which polychlorinated aluminum is added; a sixth water tank to which macromolecular coagulant is added; a seventh water tank that serves as a sedimentation tank; an eighth water tank that serves as a condensation tank; a twelfth water tank which has a stirring means and charcoal and activated carbon placed therein and into which a supernatant water from the seventh water tank is introduced; and a biotic activated carbon tower.
According to this constitution, the first through eighth water tanks have quite the same operations and effects as those of the last constitution.
This constituion differs from the last one in the following points (1) and (2). (1) The stirring means is provided, and the supernatant liquid from the seventh water tank (sedimentation tank) is introduced into the twelfth water tank filled with the charcoal and the activated carbon, the charcoal and the activated carbon adsorbing the organic matter such as the surface active agent in the waste water that can be hardly biologically decomposed. (2) After the adsorption by the charcoal and the activated carbon, the surface active agent can be biologically decomposed by the microorganism propagating on the surfaces of the charcoal and the activated carbon. The twelfth water tank filled with the charcoal and the activated carbon is arranged before the biotic activated carbon tower. Therefore, the twelfth water tank serves as the pretreatment tank to allow the function of the biotic activated carbon tower to be consistently maintained. This reliably obviates the need for the activated carbon regenerating work in the biotic activated carbon tower.
In an embodiment of the present invention, the waste water treatment equipment further comprises a sludge returning means for sending the sludge precipitated in the seventh water tank or the sludge condensed in the eighth water tank or both kinds of sludge back to an upper portion of the second water tank.
According to this embodiment, the sludge precipitated in the seventh water tank or the sludge condensed in the eighth water tank or both of them are sent back to the upper portion of the second water tank. Therefore, the microorganic concentration in the upper portion of the second water tank can be increased. In addition, this microorganism has passed through the seventh water tank (sedimentation tank) and the eighth water tank (condensation tank). Therefore, the anaerobic microorganism becomes dominant to allow the anaerobic sludge zone to be constructed in the upper portion of the second water tank. If the anaerobic sludge zone is constructed, then the nitrate nitrogen (NO3xe2x80x94N) in the waste water can be denitrified into N2 gas.
In an embodiment of the present invention, the waste water treatment equipment further comprises a first biological treatment means for biologically treating the waste water containing a high-concentration surface active agent by means of a high-concentration microorganism with a separation membrane; and a second biological treatment means for biologically treating the treated water from the first biological treatment means by means of a charcoal and activated carbon water tank filled with charcoal and activated carbon, the treated water treated by the first and second biological treatment means serving as a biologically treated water to be introduced into the third water tank.
According to this embodiment, the waste water containing a high-concentration surface active agent is biologically treated by the high-concentration microorganism with the separation membrane. Therefore, the surface active agent that can be easily biologically treated is removed, and the waste water including the surface active agent that can hardly be biologically treated passes through the separation membrane. Then, the filtered waste water flows into the charcoal and activated carbon water tank filled with the charcoal and the activated carbon. In this charcoal and activated carbon water tank, the microorganism for decomposing the surface active agent that can hardly be biologically treated is propagating using the charcoal and the activated carbon as a carrier for fixation. That is, the microorganism for decomposing the surface active agent that can hardly be biologically treated is propagated and cultured in the water tank filled with the charcoal and the activated carbon, allowing the biologically treated water capable of more efficiently treating the surface active agent in the waste water to be introduced into the third water tank (aerobic tank).
That is, the microorganism that has been accustomed to the surface active agent that is hardly biologically decomposed has a capability for decomposing every sort of surface active agent. By mixing the biologically treated water that includes the microorganism having an excellent degradability to the surface active agent into the third water tank (aerobic tank), the surface active agent in the waste water can be easily efficiently treated.
In an embodiment of the present invention, the waste water treatment equipment further comprises an eleventh water tank for mixing at least one of the sludge precipitated in the seventh water tank and the sludge condensed in the eighth water tank with the biologically treated water from the first and second biological treatment means and thereafter introducing the resulting mixture into the third water tank.
According to this embodiment, the biologically treated water and at least one of the sludge precipitated in the seventh water tank and the sludge condensed in the eighth water tank are mixed with each other in the eleventh water tank and thereafter introduced into the third water tank. Therefore, the microorganism is fixed in the sludge, and the surface active agent in the waste water can be treated by the microorganism adapted to the decomposition treatment. Therefore, the surface active agent can be efficiently treated. That is, the microorganism having an excellent degradability of the surface active agent is fixed in the sludge in the eleventh water tank of another system and then cultured and propagated. Thereafter, the sludge is introduced into the third water tank so as to more efficiently treat every surface active agent in the waste water.
In an embodiment of the present invention, the eleventh water tank mixes at least one of the sludge precipitated in the seventh water tank and the sludge condensed in the eighth water tank with the biologically treated water from the first and second biological treatment means under aerobic conditions and thereafter introduces the resulting mixture into the third water tank.
According to this embodiment, the biologically treated water and at least one of the sludge precipitated in the seventh water tank and the sludge condensed in the eighth water tank are mixed with each other in the eleventh water tank and thereafter introduced into the third water tank. Therefore, the aerobic microorganism is fixed in the sludge, and the surface active agent in the waste water can be treated by the aerobic microorganism adapted to the decomposition treatment, allowing the surface active agent to be efficiently treated. That is, the aerobic microorganism having an excellent degradability of the surface active agent is preparatorily fixed in the sludge in the eleventh water tank of another system and then cultured and propagated. Thereafter, the sludge is introduced into the third water tank so as to more efficiently treat every surface active agent in the waste water.
According to this embodiment, the aerobic microorganism that has preparatorily been accustomed to the decomposition of the surface active agent is fixed in the sludge. Therefore, if the microorganism is introduced into the third water tank (aerobic tank), then every sort of surface active agent can be treated more efficiently.
In an embodiment of the present invention, the eleventh water tank mixes at least one of the sludge precipitated in the seventh water tank and the sludge condensed in the eighth water tank with the biologically treated water from the first and second biological treatment means under anaerobic conditions and thereafter introduces the resulting mixture into the second water tank.
According to this embodiment, the biologically treated water and at least one of the sludge precipitated in the seventh water tank and the sludge condensed in the eighth water tank are mixed with each other under anaerobic conditions in the eleventh water tank and thereafter introduced into the second water tank. Therefore, the anaerobic microorganism is fixed in the sludge in the eleventh water tank. Subsequently, this sludge is introduced into the third water tank. Therefore, the treatment can be activated by the anaerobic microorganism adapted to the decomposition treatment of the surface active agent in the waste water, allowing the surface active agent to be efficiently treated.
Since the sludge zone is formed in the second water tank, the concentration of the anaerobic microorganism that has been accustomed to the decomposition of the surface active agent can be kept high. Consequently, not only the surface active agent in the waste water but also the nitrate nitrogen and hydrogen peroxide can be more efficiently treated.
That is, according to this embodiment, the anaerobic microorganism having an excellent degradability of the surface active agent is preparatorily fixed under anaerobic conditions in the sludge in the eleventh water tank of another system and cultured and propagated. Thereafter, the anaerobic sludge is introduced into the second water tank. With this arrangement, every surface active agent in the waste water, including the nitrate nitrogen and hydrogen peroxide that can be treated by the high-concentration anaerobic microorganism, can be more efficiently treated.
In an embodiment of the present invention, the treated water from the biotic activated carbon tower is introduced into a biotic monitoring water tank provided with a TOC (Total Organic Carbon) meter, and the stirring means of the twelfth water tank is controlled by the TOC concentration of the biotic monitoring water tank.
According to this embodiment, the surface active agent concentration can be easily controlled by replacing the surface active agent concentration that requires much time for the measurement with the TOC concentration that can be automatically measured in a short time. That is, by measuring the TOC concentration that can be consistently automatically measured on line to the ppb order instead of the surface active agent concentration that requires much time for the measurement, more accurate waste water treatment water quality control can be achieved.
If the TOC concentration is too high to achieve a specified treatment condition in the biotic monitoring water tank, i.e., if the water quality is bad, then the stirring means of the twelfth water tank is controlled to allow the treatment performance to be improved.
The surface active agents include an anionic surface active agent, a cationic surface active agent and a nonionic surface active agent. An high-grade measuring device is necessary for measuring the concentration in the waste water, but currently no practical automatic measurement of such high-grade has been established. That is, two to three days are necessary at the earliest after sampling the waste water. The on-line automatic measurement is to sample the waste water by a pump, introduce the waste water into an automatic measurement device through piping and measure the specified component in the waste water. It is to be noted that the items that can be currently automatically measured on line include COD, a fluorine concentration and so on besides TOC.
In an embodiment of the present invention, the biotic monitoring water tank is provided in a blower chamber and an aquatic living thing is bred in the biotic monitoring water tank.
According to this embodiment, the biotic monitoring water tank is provided for the blower chamber. Therefore, the waste water can be stably evaporated and condensed by the heat generated from the blower itself stably throughout the year without providing any new evaporation and condition equipment. Then, the waste water is introduced into the biotic monitoring water tank and condensed there. Therefore, even if the water quality of the treated water at the exit of the biotic activated carbon tower has low values with regard to all the items that may influence the living thing, the influence on the living thing can be swiftly confirmed by increasing the concentration of harmful substances by condensation.
Furthermore, the aquatic living thing is bred in the biotic monitoring water tank. Therefore, if an aquatic living thing that is influenced by the surface active agent even in low concentration and an aquatic living thing sensitive to the environment are selected, then the influence of the treated water including the chemical substances such as the surface active agent on the living things can be comprehensively confirmed.
In an embodiment of the present invention, the stirring means is a pneumatic stirring means for executing stirring by air.
According to this embodiment, the stirring means of the twelfth water tank is the pneumatic stirring means. Therefore, the inside of the tank can be stirred by the upward flow of the aeration by air, and the organic matter such as the surface active agent in the waste water can be biologically treated by the aerobic microorganism that is propagating on the surfaces of the charcoal and the activated carbon. By virtue of the aerobic microorganism propagating on the surface of the activated carbon in the biotic activated carbon tower in the next process, the dissolved oxygen concentration in the waste water in the twelfth water tank can be increased. As a result, the waste water having a high dissolved oxygen concentration can be introduced into the biotic activated carbon tower.
Therefore, since the stirring means is provided by the pneumatic stirring, the organic matter adsorbed by the activated carbon can be treated by the aerobic microorganism propagating on the surface of the activated carbon without taking out nor regenerating the activated carbon in the biotic activated carbon tower, and the state in which the activated carbon can always be regenerated can be practically maintained. It is to be noted that the biotic activated carbon means the activated carbon in a state in which the organic matter adsorbed by the activated carbon is treated by the microorganism propagating on the surface of the activated carbon as if the activated carbon is regenerated.
In an embodiment of the present invention, any one of a group consisting of: a snail such as a marsh snail; a guppy; and Oryzias latipes is selected as the aquatic living thing.
According to this embodiment, any of the snail such as a marsh snail, guppy and Oryzias latipes is selected as the aquatic living thing. Therefore, only if the water temperature and water quality of the waste water are controlled, the eggs of the aquatic living thing can be hatched within a short period of one to three months, and the influence of the chemical substances of the surface active agent and the like on the alternation of generations of the aquatic living thing can be confirmed.
That is, according to these embodiments, the optimum water for breeding the aquatic living thing is made by maintaining the water temperature of the biotic monitoring water tank utilizing the heat generated from the blower and treating the waste water by the twelfth water tank (biotic activated carbon tank) and the biotic activated carbon tower. Therefore, even if no decision is made as to whether or not a chemical substance in the waste water might be a hormone disrupter, then it can be easily confirmed whether or not the chemical substance such as the surface active agent in the waste water might be a hormone disrupter since the aquatic living thing exhibits alternation of generations several times within a short period in the environment where the eggs hatch most easily. It has already been discovered through experiments that the aquatic living things can be easily bred in the treated water treated by the aforementioned biotic activated carbon tank and the biotic activated carbon tower. The aquatic living thing means all sorts of living things such as fishes and snails living in the waste water.
In an embodiment of the present invention, the return sludge is introduced into the first water tank.
According to this embodiment, the return sludge is introduced into the first water tank. With this arrangement, the waste water can be pretreated by the unreacted slaked lime and the unreacted coagulant even if the water quality of the waste water abruptly changes to the higher concentration side. Therefore, the posttreatment after the pretreatment can be stabilized. The return sludge is in a muddy state. However, the unreacted slaked lime and the unreacted coagulant sludge can be dissolved in the acid waste water so as to be brought into a solution state, or a state in which they can easily react. According to this embodiment, the return sludge is introduced into all of the first, second and third water tanks. Therefore, the unreacted slaked lime and the unreacted coagulant in the return sludge are brought in contact with the waste water for reaction for a long time, by which the unreacted slaked lime and the unreacted coagulant can be utilized more effectively.